1. Field of the Invention
The present invention relates to an apparatus for the treatment of substances, comprising a rotationally symmetrical container and a tool shaft which is mounted concentrically relative to a container axis and has at least one stirring member.
The apparatus can be used, for example, for drying of pharmaceutical active substances, natural remedies and fine chemical products and products of the food industry. It is possible to dry relatively large batches in a relatively short time in a container. The drying process can be carried out, alternatively and dependent on the substance to be treated, under atmospheric pressure or in vacuo. For example, an apparatus can readily be designed for drying batches of the magnitude of 1000 kg, it being possible, depending on the characteristics of the substances, to dry such a batch in a relatively short time, which is only a few hours or even less than one hour.
However, the apparatus can also be used for the preparation of powder blends, granules and the like, for example food and pulverulent drugs.
2. Description of the Prior Art
In the preparation of many substances of industrial and private use, which are also referred to below as materials, it is frequently necessary to mix different types of ingredients with one another. In various cases, it is also required to bring about a chemical reaction in the mixture. The uniform distribution of the individual ingredients of the mixture is sometimes resisted to a considerable extent by individual components. In such mixing processes and particularly in drying processes, relatively high pressures result. In order to be able to absorb such pressures, apparatuses for drying a material which have a spherical container have already been developed. A particular advantage of this apparatus also referred to as a ball dryer, is that they have a pressure shock resistance which is higher than that of apparatuses having a container, for example a cylindrical one.
Known ball dryers are intended for batchwise operation and have a spherical container with a wall containing a heating and cooling device, a stirrer introduced from below into the interior of the container and at least one feed device arranged on the upper part of the container and connected via an inlet to the interior of the container. Optionally, a homogenizer, also referred to below as a shredder, can additionally be rotatably mounted in the container.
If, for example, a dry material intended as a food is prepared using the known apparatuses, said material is introduced into the interior of the container via the feed device. The material is then agitated and mixed by means of a stirrer, optionally further components and additives, such as, for example, liquids, colorants and the like, also being added to the material during the mixing and/or drying process.
In the case of a ball dryer standing on a frame in the production room or clean room of an industrial facility, the material outlet and also the drive device of the stirrer are arranged on the lower part of the container. This has important disadvantages with regard to compliance with hygiene regulations in the production of, for example, drugs and food. In such cases, it is in fact necessary for those machine parts of the stirrer which are arranged outside the container, i.e. said drive devices, to be spatially separated from the material outlet by a housing enclosing said drive device, i.e. by additional constructional measures.
Moreover, such an apparatus is difficult to clean and maintain. Thus, both for removing the feed means and in particular the stirrer and also for cleaning the interior, the upper part of the container has to be removed with relatively great effort, whereupon the stirrer is removed from the spherical container from above. Furthermore, this manipulation complicates the cleaning of the entire apparatus and the subsequent assembly, particularly when the cleanliness of the internal container part has to meet high requirements.
It is the object of the invention, starting from a ball dryer, to provide an apparatus for the treatment of substances which does not have the above-mentioned disadvantages. It is intended in particular to retain a rotationally symmetrical, for example spherical, container shape and to provide a construction which makes it possible to dispense with constructional measures for shielding parts of the apparatus and which permits simple removal of the stirrer and the like.
This object is achieved according to the invention by an apparatus comprising a rotationally symmetrical container, a material inlet opening into the interior of the container and a material outlet leading out of said interior, a stirring unit having a shaft and at least one stirring member. The apparatus is further characterized in that the container has an upper and a lower half-shell each having a vertical axis of rotation, that the material inlet is arranged in the upper half-shell and the material outlet is arranged in the lower half-shell, that the lower half-shell can be separated from the remaining part of the container and that the shaft of the stirring unit is rotatably about a vertical axis or an axis which is inclined not more than 30xc2x0 and is connected to a drive device arranged on the upper half-shell.
The container of the apparatus according to the invention consists of two half-shells and has essentially the shape of a body of revolution with a horizontal and a vertical plane of symmetry, i.e. is rotationally symmetrical with respect to a horizontal and a vertical axis of rotation. The container preferably has the shape of a sphere with a material outlet arranged in the bottom of the lower half-shell. A stirrer which is rotatable about a vertical axis or via an axis inclined at most 30xc2x0, preferably 15xc2x0 to 20xc2x0, and which is connected to a drive device arranged on the upper half-shell and, during operation of the apparatus, picks up the entire material and constantly circulates it is arranged in the container. The apparatus is suitable as a dryer, a mixer and, with introduction of a suitable liquid, also as a granulator and can be used not only for chemical synthesis but also in combined applications in the pharmaceutical manufacturing stage. Particular advantages of the apparatus according to the invention are the pressure surge resistance and the simple maintenance, cleaning and monitoring of the cleaned components.